HOUSTON – The postgame music wasn’t any louder. There was no additional yelling in the clubhouse or extra celebrations.

It might seem strange, but this — winning — is expected. This is the 2014 Mariners.

Seattle capped a series sweep of the Houston Astros on Wednesday afternoon at Minute Maid Park, getting yet another outstanding start from Chris Young and rallying from a 2-0 deficit with a four-run sixth inning en route to a 5-2 win.

The Mariners won their fourth straight game and have won 10 of their past 12 to improve to 47-38. It’s the first time a Mariners team has been nine games over .500 since the end of the 2007 season.

But there was no giddiness. It’s part of the attitude that was pushed by manager Lloyd McClendon in spring training, tested by an early eight-game losing streak and forged by surprising runs of success where they’ve found ways to win games they shouldn’t.

It’s a businesslike confidence, an ability to move on each day that hasn’t been evident in the organization in some time.

“We’re an even-keeled group,” Young said. “The highs aren’t too high and the lows aren’t too low. We’ve been through an eight-game losing streak and I don’t know what our winning streaks have been and I don’t think anybody cares. We know it’s a long season and there’s a long way to go. We still have a lot to prove, and we haven’t played our best baseball yet.”

And yet they’ve had success, which is surprising to many but not to them. They believe they’re a good team and they’ve earned it.

“I think you are seeing day in and day out what we are capable of doing,” said Dustin Ackley, who had three hits. “I don’t think you can say it’s a fluke anymore. I think everybody is starting to see that this is what we are capable of doing.”

For the second straight day, the Mariners broke the game open in the sixth inning. On Tuesday, they scored seven runs on six straight run-scoring hits.

Before Wednesday’s sixth inning there had been no sign of offense from the Mariners. The Astros were up 2-0 and Houston starter Brad Peacock had cruised through five innings, allowing three hits and striking out five.

“Early on we were pretty flat,” McClendon said.

But it all started to unravel with one out in the top of the sixth. James Jones singled to left. Peacock hit Robinson Cano in the back of the leg with a pitch and walked Kyle Seager, throwing several pitches in the dirt well in front of the plate. That trend continued with the bases loaded and Logan Morrison at bat. One of those dirt balls bounced past catcher Carlos Corporan all the way to the backstop, allowing Jones to score on a wild pitch.

Peacock made an adjustment and stopped spiking his pitches in the dirt. Unfortunately, it meant he left them over the plate. Morrison took advantage, doubling down the right-field line to score two runs and give the Mariners a 3-2 lead.

John Buck followed with an RBI single to score Morrison.

A 4-2 lead was plenty for Young. The veteran right-hander turned in one of his best starts of the season, pitching seven innings and giving up two runs on two hits with a walk and a season-high eight strikeouts.

“I don’t know where we would be without him,” McClendon said. “He’s done a tremendous job for us, and today was no different. It was a quality start from start to finish. He gave us an opportunity.”

The two hits were solo homers.

Marwin Gonzalez hit one in the third inning and Kike Hernandez added one in the fifth. Otherwise, Young was flawless, getting his usual mix of off-balance swings and pop-fly outs to improve to 8-4.

“I felt for the most part I made very good pitches,” Young said. “I kept them off balance, really had two good off-speed pitches today and good fastball command. I was pleased. There are going to be days you give up home runs and you hope they don’t beat you. The guys came back and picked me up, and the credit goes to them.”

Seager stretched the lead to 5-2 with an RBI single in the seventh inning.

The Mariners’ bullpen closed out the game. Danny Farquhar and Yoervis Medina worked a scoreless eighth inning and Fernando Rodney pitched a 1-2-3 ninth to notch his 24th save.

Ryan Divish: 206-464-2373

or rdivish@seattletimes.com.

On Twitter: @RyanDivish

Ryan Divish: 206-464-2373 or rdivish@seattletimes.com; on Twitter: @RyanDivish. Ryan Divish covers the Mariners and offers his perspective all season. He gives his inside look at Major League Baseball and power rankings every Sunday.